Static neutralizer for radioreceivers



May 9, v1933. e. w. PICKARD 1,907,572

STATIC NEUTRALIZER FOR RADIORECEIVERS Original Filed Oct. 5, 1918 7'0 OPEK/ITORS Face/mm.

Patented May 9, 1933 ennnnrnnr wnrr'rrnn PIGKAREOF NEWT01\T,: CENTER, mnssncnusnrrsnssrenon, A BY MnsNE A$SIGNMENIS, oe rrnRnL nneornrcgcoiv rAngfln conronnriton F by theaerialsand .at thesame time secure New YoRK' This applicationv is a continuation of an v application, Serial Number 256,978, filed by i I, 'me October 5, 1918 and a continuation in part of an application Serial No. 368,903 filed by 5 me March 26., 1920.

This invention relates to receiving appa ratusv and method employed in radio com- I munication, and its object is to' prevent' static from .interfering,'at the receiving appara-, 9 tus', with the useful energy received from a j distant transmitter (static being the common name for atmospheric electrical 'disturb ances). i

i 1 In practice, theembodiment of this inven- 1.31

tion'which is shown in the drawing and herethe improvement of the ratio of signal intensity to static intensity twenty-four times, which is equivalent to an elimination of ninety-six per cent of the. intensity of static received at the receiving station.

suflicient signal energy to be useful.

This objectis preferably attained by employing a plurality of collectors or aerials ,,.properly positioned or having different di :rectional properties in any desired plane and 1 suitablyv coupled to combine the. energies-rej ceived. The intensity of the signal and static received by a directional system varies, of

Y (course, with the position the aerials occupy with respect to the wave fronts. Such a sysytem should preferably belocated to receive the greatest amount of signal consistent with 7 total elimination of static, and any-adjust- 'Inents, other than the above, necessary to eliminate the static, is done by means of the couplingbetween the aerials, or by means of the other adjustments hereinafter more fully described, or both.

bodiment showing the .operators switches which may be employed in practice.

A is an aerial or antenna or collecting cirgreatly diminshed.

STATIC 1t summarize-1R FOIt nnnronnonrviins This applieationfiled 1901a 6, 1920.

cuit 6 of any type ordinarily used, including a primary coupling-coil 1?; thesecondary coupling-coil being at. T and connected to the receiving ;or indicating: apparatus and circuits,- such as fa detector 'andtelephone receiver or the like as commonly used in the radio art in various ways. Qf course, all the coupling-coils, as; well, as the tuning condenser C, are; most conveniently located in the vicinity of theoperators receiver, and not up in theair as'mightbe inferred from the diagram.

Inaddition toantenna, A, one (or more) additional collecting. circuits is employed, such as B, which is a directional form of colsignal waves, {Although circuit Bmay assume various formsof directional circuits, yet it preferably I consists V ofand in; such casesis disposed so asto actas) a magnetic 1inafter described" has resulted thus far in lector, i. e., operates best when disposed with I respect to the direction of the transmitted loop, as described in myPatent No, 876,996. g

Circuits A and Bare connectedtogether at point-X, sov that the wires- A. B,'.Whl0l1 constitute the magnetic loop'B, alsofact as anupper part ofja-ntenna A.

It is very}; desirable, at least, that the difference between the amounts of .static energy tending to be induced upon secondary T by the two circuits respectively be less than the algebraic sum of; useful; signal. energy tending to be 'so induced bythe two circuits,

respectively. I I

The static disturbances arrive {at the receiving station from various directions in altitude and. azimuth, which, of course, afiect the aerials. Possibly a larger'proportion of the static comes from ahorizontal direction.

According to my observatons ontheNorth Atlantic Coast, the less 'bothgnsonie v forms of static appear to come indeterminately J from all points inthe hemisphere above, with a c t i prepond r n oward t e the more bothersome forms of static, however, are localized and occur at intervals, so that, bysuitable adjustmentsof the apparatus, hereinafter described, its efi'ect may be Directional aerialsor combinations of directional aerial and open antenna herebefore nated by either proper adjustment of the po sition of the apparatus or by manipulation of the couplings and other adjustments. It

- is, therefore possible to eliminate, by means i loop, a large. percentage of the more bothermost severe conditions.

of the combined open antenna and magnetic some form of static, but this is not enough for practical operation.

The objectof the present invention is, therefore, to improve upon present construe tions and to provide adjustments and methods of eliminating enough static .so that the ratio between static and signal will be such as to render the signal audfbleunder the Of collecting circuits A and B,the magnetic loop B issuch a directional or signalreceiving circuit as above indicated, and in the practiceof this invention it is preferably located with its plane normal to the vertical plane ofthe magnetic circles or lines in the advancing wave front, i. e., the plane of the loop is vertical to the earth and in line with (pointed at) the distant transmitter, all as described in my said Patent No. 876,996. Thus loop B is a directional circuit, and disposed to function as such and therefore to receive the signal waves veryefficiently.

The circuit A, as here illustrated, is substantially non-directional in a horizontal plane, but it is to be understood that other types of aerials arranged in different positions may be substituted therefor.

The collectors A and B receive from the Waves bothsignal and static energies, as

hereinafter fully described, where the static energies are neutralized and sufiicient signal energy retalned to be useful.

Collector B includes the pr mary couplingcoil T which, through primary couplingcoil T in collector A, supplies energy to the secondary coupling-coil T.

In accordance with this invention, the greater part of the static energy received at the receiving station is prevented from reaching the circuit of secondary coil T or, at

least, such a large proportion of the static is eliminated from the receiving system that too little exists in the secondary circuit to prevent the operator from intelligibly reading the signals. This result is obtained in the following manner.

Equalization of static energies static energy, they never receive the same amounts save by accident, and in order to eliminate the greatest proportion of the energy due to static,tl1e electromotive forces due to static which are induced, across secondary coil T by primaries T and T in collectors A and B respectively, are made equal by coupling adjustment. Such equalization is permitted to be done by the operator, by providing variable couplings between coils T and T and between coils T and T respectively, such couplings being indicated at K and. Q,respectively, by conventional symbol, and comprising any of the known constructions permitting variability of coup1ing-adjustment by the operator. By adjusting the couplings Q, and K relatively to each other, the coupling between the coils T and Tfmay be varied.

Neutralization of static energies pared with either of the received static electromotive forces in collectors A and B prior to neutralization. This setting in. opposition is effectuated by so connecting one of the primaries, T or T in its own collecting circuit, that the electromotive forces due to static set up across secondary coil T are in opposite directions. The means for doing this in a practical manner is described more particularly later on in connection with Fig. 2.

Prepondemnce of signal-energy ance with the direction from which the static comes, or the relation between the wave fronts set up by the static discharge and the aerials. The prime purpose of the invention is to oppose and equalize the static received by the aerials to eliminate the greatest possible amount. In some cases this will necessitate the sacrifice of a comparatively large amount of signal energy received by two aerials, especially if the static discharge is in the direction of the transmitting station. In such cases, the setting in opposition of the static energies received by the collectors A and B is accompanied bya setting in opposition to each other of the signal energies received by the collectors A and B. Inas much as the static discharge rarely, if ever,

comes from a point-in line with the transmitter and receiving'station, byreason of the unilateral 'directive properties; of the system, suflicient' signal energy will" remain after eliminating static to be useful.

This preponderatingorremaining electromotive force of signal energyreceived by collectors A and B is's'uflicientto operate the indicating apparatus so that the signals are, lntelliglble'to the operatora In fact, even if the static be not completely eliminated or excluded from the secondary 'circuit by the action'of neutralization, yet 'the'ratio of'signal intensity tostatic'intensity'in'the'secondary circuit is-so greatlymcreased bythe use of this invention that always signals can be read under su'ch'bad conditlons of statlc'i'nthe atmosphere as otherwise would prevent intelligibility of even strong signal responsesr Thus, for example, take the actual instance of a use by me of the embodiment of Fig; 1 (data of which chances to 'benow at hand), wherein, at a given instant, collectorsAand B were receiving energy as follows, in terms of units of signalswhich would be barely,

audible in the absence of static:

- Collector A Signal 600 Static 4000' Collector 13 i Signal 2000 if Eatatic 5000' Thereupon thestatic energies-from the collectors are'made more nearly equal in their eifect upon the'secondary by the coupling adjustments. This coupling adjustment might have been done in either or both of SignallGOO' Static 4000 hus the static'wa's apparently equalized iii-collectors A and B, the secondary (T receiving six hundred audible signal units from collector A, as noted in the first above schedule. (All the above figures represent actual measurements.) The resultthereupon, of setting in opposition the two totals'of electro motive forces from A and B, would produce, according to theory, zero static energy'ln' the secondary (T and would produce useful signal energy inthe secondary (T of sir:- teen hundred minus sixhundred, or one thousand times audibil-ity. In fact,-however,

actual measurements showed-the result in 'the secondary circuit (of T to be'as 'follows'rjig al 0 StaticiiiOO Comparing this result with that in thecase of using collector alone ('receivingzsignal 2000, static 5000 as above) it'is seen that the use-of this invention gave an improvement 1 a of the ratio of intensityof signal to intensity? of static, in the secondary circuit,"from four-a tenths ofa unit to six units,'i. e., an improve-j ment of fifteen times.

The above difierence'betweenthetheoret ical resultand the actualresult'is'believed to befdue, (a) to unavoidable losses of signal energyin any embodiment of the invention,

and: (b) to the intentional omissionto use or employ. "refinements of operator?s adjustments and re-adj ustments for equalization. and neutralization which if used'would pro-F duce'aresult which would be an improvement but not worth the time necessarily consumed. A valuable feature 'of the invention 1 is the magnitude of improvements" obtained by a simple adjustments quickly made. As a prac- ,7 t-ical matter, all that is necessary to be accomplished, for example, is the elimination of a" sutficient portion of the statictoprevent a static response which shall be, say, anymore intense than the signal response; and that'is accomplished readily by this invention by an. ample margin without adjustments consuming much time, as indicate-d by the above example showing a result in the secondary circuit of useful energy six times as; great as static energy; while without the employment of the invention, the intensity of static response would have been, from circuit'A, nearly seven times as great as the signal 'zresponse, and from circuit BJthe intensity of static response would have been, nearly three times as great as the signal response.

Before equalizing and neutralizing the static,'the operator is'to tune collector'B to l a i the transmitted signal-waves untilhis tele phones indicate the greatest intensityfof sig nal response. This he may do-by adjustment of condenser C orof inductance T orboth.

This tuning may be done, however, at any" stage of. the operations if desired, as for ex,-

ample in a case where the'st'atic is at first too." bad to enable the operator to distinguish thew signal with sufficient clearness to permit accurate tunlng. I

Also, before making the coupling-adjust ment for equalizing the static, primarycoils T andT- are assumed to be so connected to.

each other with respectto "secondary coil T as to permit'neutralization of the equalized as to the switches of Fig 2 static (see infra, employed in'practice).

Also, before making any of the operators' adjustments for executing the invention, a each of the primary coils'T' andT is assum'e'd to be mediuml'y loosely coupled-to see ondary coil T as a condition precedent to the coupling-adjustment for equalization. 1

The collector A is also provided with an inductance coilL, constructed to be adjustable and variable forthe purpose of tuning,

which can be done at any time that the opera-i tor deems convenient and advantageous.

It has been found that complex wave formationa'or coupling waves, are set up in systems such as here disclosed, in which a plurality of aerials are coupled to each other, as by way of a secondary circuit. These complex wave formations are especially notice able where the collectors are excited by aperiodic or single pulse waves, such as static. These formations are not as noticeable in connection with, the signalwaves, as the lat-:

ter "are but feebly damped and theypersist for a long enough time to permit an. opportunity to set up. a wave train in which there are no complex wave formations."

These complex wave formations are such a nature that a large percentage of their energies transferred to the secondary cannot be eliminated by coupling adjustment. I

have devised means for overcoming and pre-.

venting thesecomplex wave formations or coupling waves.

This means, in the form here illustrated, comprises a resistance R, shown as a noninductive resistance. As here illustrated, this as without the resistance the open antenna would receive a larger amount of energy. The resistance R is ad ustable andcan be ad usted by the operator until as noted by the ear at the receiving telephonethere is a.

marked decrease in static response. The nee essary amount of resistance, of course, depends upon the other characteristics and constants of the system and upon the received wave length. The specific resist-ancethat I used in an actual constructionisdescribed more fully. hereinafter.

Irrespective of the nature of the electrical operations that are taking place incthis system, which I believe to be due to the complex wave formations above described, I find that the insertion of a resistance, such as R, in either aerial or both, where such coupled aerials are employed, produces surprising results in eliminating static.

After the adjustment of the resistance R, or after adjustment of any of the other parts of the apparatus, particularly the couplings, it may be againn'ecessary toadjust the coil L and the condenser Gto re-tune the circuits and. further decrease the static.

The amount of resistancewR necessary in a given. system depends, of course, upon the extent of adjustment, or upon the tightness or looseness of the, couplings between the aerials and the secondary circuit. fore, if these couplings are tightened or loosened at any time, it willbe necessary to readjust theresistanceR. This can be done by the-operator, who will soon learn from experience what additional adjustment of R will be needed. The coupling adjustment above described may consist of either tightening or loosening either coupling 1K or Q to increase or decrease the amount of static and signal energy transferred to the secondary circuit from collectors A- and B. The operator recognizes the best adjustment by the lowest intensity of static response in his telephone. 1

j The above series of operations, including tuning of collector B,'adjustment of R and L, and adjustment of couplings K or Q, or both, may be repeated several times, if and when desired, in ordertoeffect the best resuit or to makesure that 'the best results are being obtained. The best result is, of course, the signals which are most readily intelligible to the particular operator who is making the adjustments. Sometimes circumstances may exist where it is desirable to take the time to make such re-adjustments; and an example of such potentiality of the invention in this respect is afforded by a comparison of the two cases mentionedabove, in one of which the ratio of signal to static was increasedtwenty-four times and in the other onlyfifteen times. j 1

Fig. 2 is amore detailed diagram of the same embodiment as Fig. 1, showing the operators switches employed in practice. The parts in Fig. 2 which are the same asin Fig. 1 are lettered the same. i 1

The parts in Fig. 2 whichare not shown in Fig. 1 are the operators switches Y, V and S.

1 Switch Y] is used to locate the point X, Figs. 1 and 2, either to the'right (see Fig. 1) of coil T or tothe left of condenser C: I have found thatunder any given set of circumstances one or the other location of point X permits markedly better results i. 6, less static response) than the other. Switch Y is a single-pole double-throw switch, as is shown. It may be worked at any stage of the operations, but the preferred stage is described later on. j 1

Switch V. is a reversing switch, by which primary coil T and inthe presentshowing condenser C, are reversedin their connection in their circuit 13, and coil T is reversed. with relation to secondary coil T and primary coil T. Switch V is a double-pole, double- Therethrow switch, and its connections, are clearly shown. I v

The switch V is important inasmuch dasgby'. throwing this switch to one position or the. other the amount of. static received isrenor-c mously increased or enormouslydecreased, according to the CllIGCtlOll from which 1t is comlng. At any rate, the switchY- should he so arranged as to set the static energies re ceived by the aerialsrin opposition inthe secondary.

Switch S has been supplied to reverse the primary coils T and T with respect toeach other and with respect to the secondary coil ful in order to secure'refinements of adjustment by reason of the fact that in such'a grouping of coils as T, T and T there are present not only magnetic or inductive couplings but electrostatic couplings as well, and, hence, the reversal of coil T with respect to T may have a different effect upon the sec.-

ondary T? than. the reversalof coil T' ,.Wlth*;

respect to T.

The operator may switchesto obtain the best results as determined .by. trial. and observance of telephone J response during static conditions. The proper arrangement of coils for neutralization should ex st before the operator begins to adjust R or L or the couplings K or Q, or both,

or refinements of adjustment-,or for the purposes of equalization of the static. If switch V or S, or both, beused, .the;operator,;after determining by the response in the telephones the" correct position of switch V, next determines by similar trial'the correct position of switch S, and then he begins the adjustments ofL,R,QandK.

Switch S is also a double-pole, doublethrow switch, and its connections areclearly shown.

It is clear thatthe switches of Fig. 2 and their connections maybe rearranged or combined in various ways to efiect the same results as herein described.

Summing upwith reference to Fig.2, th

steps by which the invention is executed are i as follows, .and generally iinthe following order: 7 I r "1. In installing directionalcircuit B in respect' of a given transmitter, it is moved to point more directly toward the distant trans-- mitter, whilebeing kept-vertical, until the loudest signal-response isheard in the telephones, which willindicate that it is in line with the transmission. Y Y 2. Collector B is tuned to the'length of the transmitted signal-waves, as by adiusting condenser G or inductance T or both. At this stagethe switch S must be open,-as each then adjust zthese 'mine,by

tion, which location of point X .givesthefi Aaerial'ispreferabIy tuned separately. The

collector Afis :thentunedby any suitable; means, such-as the inductance ;L, the switch S H in this instance being closed and the switch; [V open. Both switchesV, and S are then I -'V closed; Generally,-;better results may be-ob- 1:: tained if this step is repeated-after somewor each .cf the subsequent steps of adjustment,

becausethe latter, (as the coupling adjustments) areliable to affect the wave-length of;-

circuit'B. Such subsequent tuning adjust ments ofcircuit B, however, generally do not w 7 require as much time as the first tuning. v V

couplings K and Q to a con- 3. Adjustin dition ofzlmedi'um' loose coupling, in" order 4:. Operation ofswitch closed positions, alternately, in order to'determine,- by the much weaker intensity Of that, later on, they may be tightened or ,fur- :ther loosened respectively. 7

S to each ofits tWO static response in the telephones in one posi-t tion of the switch, that in that position :pri-

mary' coils T and T aref in-proper position 7 secondary coil T so that the amounts of relatively. to each otherfand with respect to V static: received by- A and ;B,frespectively, ar

in opposition and, to a preliminary degreey' neutralized in respect of their effecton secondary T 5. Tightening or or loosening or tightening: couplingiQ, or

loosening of coupling rK 5 both or'all, 'inorder to make more nearly equal} Z the inducedeii'ecton: secondary T of%t.he" amounts of static energy received in A andB- as the result of .adjustingRand L. '1 1 6 and 7. The resistance R and inductance L, oreitherof them, arethen'adjusted .until- The purpose of the-adjustment of- R has already been described above, and :the adjust: ment of R and L, oreither of them, also "tends the best response is obtained in the telephonefl to make the amounts of static in the collect'orsA and B morenearly equal in intensity and frequency. 1 r 1. -8. Location of: point 'X by. switch. Y.

1110 Switch Y is closed in each of its two positions alternately, to enable the operator tozd'eter- 3 v the telephone response at each posifwealrer response to static, that beingthe posi:

' tion in which the switch is left. i i

9. Reversing the connections of T C, inclusive Switch 7* is for this purpose op,- I

erated eitherbefore or after switch Y, and either of them may beoperated at any stage,- 5 1 v but preferably directly after the tuning'of collector B, incase the static conditions are not so bad asto prevent ashowing'of differ-z; ent intensity of staticpresponses for the re-;

spectiv'epositions of each switch; :2.

When switch S has been operated;;(as inw step 4 above); to obtainthe conditionoof neutralization, then whenever thereafter switch V is reversed from'the position it occupied at the neutralization position of switch" i S,

switch S must be reversed simultaneously with switch V, in order to preserve the con dition of neutralization. The reversal of switch V alone, byits reversal of the loop with respect to condenser C and primary coil T would not only destroy the condition for opposition and neutralization which was obtained by the proper setting of switch S, but such destruction in turn would mask the effect of the preferred relation of the loop B to condenser C and coil T to be obtained by the proper setting of switch V. Hence the operator cannot determine, by the telephone response, the correct setting for switch V without simultaneously reversing both switches V and S. By such simultaneous reversal is meant a reversal of both said switches at or about the same time for the purpose of enabling the operator to judge best as to the telephone response for the two positions of switch V.

10. Another operation of switch Y to determine the better location of point X under the conditions resulting from the above steps will show. sometimes that this switch now ought to be reversed from its previous better position.

It is clear, not only that the above series of steps may be repeated, to obtain, by finer adjustments of C, L, B K, and Q, etcl, results still better in degree, but that most of the individual steps may be repeated at any time relative to allor any one of the other steps.

Thus, asone example, directly after above step 5, instead of operatingswitch Y, both switches V and S might be reversed, etc., etc. Emphasis is to be placed on the fact that after the condition of neutralization is obtained by the proper setting of switch S, it is necessary, in order to preserve that condition, that whenever switch V is reversed, switch S also must be reversed. H i

The above method of manipulating the specific system herein shown and described may, of course, be modified according to circumstances.

The prime purpose or object to be achieved is the equalization and neutralization of the static, at the same time retaining sufficient signal to beuseful. Other means than that here illustrated may be employed to oppose the static energies and their relative amounts, such as, for instance, the proper positioning of the aerials, especially the loop, with reference to the wave front produced by the static discharge.

In order to obtain this neutralization and opposition, it is necessary that the oscillations of the static energies received by the collectors A and B must have substantially the same amplitude, frequency and decrement or damping. In other words, neutralization only takes place when the energies are at every instant during the wave trains produced by static equal and opposite. This the particular embodiment shown in the drawing, are as follows: i

Collector B was rectangular, being. two.

hundred feet long by twenty feet high, the lower side of the rectanglebeing ten feet above the ground. Thelooplconsisted of four turns of number sixteen copper wire, these turnsbeing spacedone foot apart.

Condenser C was a variable air-condenser and had an operating range from'zero to three one-thousandths (0.003) microfarad. Primary coil T had an inductance of twenty two (22) millihenries.

twenty-two (22) millihenries.

Inductance coil L in collector vA; had a range of inductance from zero to ninety (90),

millihenries, and was variable by small steps of about one millihenry each;

Resistance Bin collector A was a noninductive resistance consisting of a carbon suitable for undamped-wave signals having a wave-length. of from ten thousand to fitteen thousand meters, such as used at present Primary coil T' had alike inductance of.

The above dimensions have been found in trans-Atlantic communication. For use:

on wavelengths longer or shorter than those stated, larger or smaller values of inductance and capacity should be used, and those may be determined approximately by the wellknown formulae for resonant circuits.

Inasmuch as it is the fact that the practical use of this invention in the trans-Atlantic service of the Government has demonstrated that it accomplishesfor the firsttime results which have been aimed at for nearly twenty years, it seems unnecessary to explain in detail the advantagesor value of the invention.

I'claim broadly:

1.111 a unilateral direction receiving system the method of selectively receiving signals from one station and substantially shutting out all other electrical energies of receivablefrequency comprising the steps of,

absorbing energy radiated by said station,

the nature of which absorbed energy is characteristic of the direction of said transmitresultant energy.

in phase, and combining said currents where by the currents resulting from energies other than the signal energy are substantially eliminated and only signal energy remains.

2. The hereindescribed method of reducing static effects on a; unilateral receiving system comprising a plurality of absorption members, which consists in absorbing signal and static energies in said members,equaliz-i ing and opposing the static energies in the said members to neutralize said energies, damping oscillations in one of said members, and detecting the 'signalzenergy, absorbed.

3. In a unilateral directional receiving sys-' tem the method of selectively receiving signals from one stationj and substantially shutting out electrical, energy offreceivable frequencies from all other stations comprising the steps of, absorbing energy radiated from said station, producing current characteristic of the direction of said station from the absorbing point, absorbing a second portion of energyfrom the energy radiated. by said station, producing current, the nature of which isnon-characteristic of the direction of said radiating station from said absorbing,

point, damping out oscillations in said energies produced by absorbed energy other than the signal energy, superimposing said energies in like amounts to produceresultant energy, and producing indications with the 4;. The he'reindescribed methodzof reducing static effects on a receiving system at a receiving station comprising a plurality of collectors having difierentdirectional prop- 'erties, which consists in receiving bothstatic waves and a maximum of plane polarized signal waves on each of such collectors, add-. ing, by differential adjustment according to the direction from which static comes, the static energies received in substantially equal and opposite amountsto be neutralized and adding the signal energies of radiovfrequency received in substaiitially unequal and opposite amounts, leaving a prepondering amount of radio frequency sign'al energy due to the optimum operationofthe more directional aerial'for useful operation of a dc tector.

I 5. The herein-describecl method of 'reducing static effects on the receiving'systein at a radio station WlllClI consists of subiecting said system to the influence of signal and.

static waves collected by a plurality of collectors, preventing the formation of coupling 7 waves in said system, adding the static energies received in substantially equal and up posite amounts to be neutralized; and adding the signalenergies receivedleaving a" prepondering amount of signal energy for'u'seful operation. i a

6. The methodoi'selectively receiving signalsfrom a desired transmitter and for substantially eliminating electrical energy radiated vfrom all other [points including the steps of, absorbing energy radiated by said transmitter in two portions, producing oscillating; currents by the energy of one of said portions which are characteristicof the directionof said transmitting source from-said point of absorption, producing current oscillations from said other-portion of energy.

which are non-characteristic of the direction of said transmitter from said absorption point, adjusting the currents produced from several portions in phase'so thatthejcurrents resulting from energy other. than signal 'energy substantially oppose, regulating the am plitude of one of the produced currents ,to

substantially thesame amplitude as the other of the produced cur-rents, combining said produced energies, damping; out oscillations,

in the combined currents, which result from:

energy other than signal energy from said transmitter, and producing indications with p 1 the resultant energy; Y e i 7 The herein described method of reduc-i ing static effects on thereceiving'sys-temat" a radio station which consists of receiving static and signal waves directionally and noiii directionally with reference to any desired] plane and at substantially the same point relatively to the wave length, preventing,

coupling waves bydainping, adding the static energies received in substantially, equal andj opposite amounts to be neutralized, and add-' ing the signal energies received leaving a p p ing amount ofv i l energyifoi; useful operation. 2 P 7 .8. 'Means for selectively receiving signals from a transmitter Zstationand for-,substan tially excluding electricalenergyorig nats ing at other pointson the compass compris ing,a, movable frame, aerial in thejformi a closed conductor, a vlumped inductancein series with said conducton'means for tuning said frame aerial to the signal frequency,=a.

vertical aerial comprising a linear conductor,

connected 'toground at one terminal, means for, increasing the; capacity of said linear aerial including s ltcl ing means for connectingsaid linear aerial to said. frame aerial at either side of saidlumped inductance, an-

inductance in said linear conductor variably,

coupled to the inductance in said frame aerial, a damping res stancein said linear conductor for damping out oscillationsof a cer-Q tain type which may appear therein, and.

means for coupling both of said aerials to a receiver. i

' a-nn arrangement as claimed 'in claiin 8 in which said vertical aerial. is tuned by means of avariable inductance in saidlinear conduct-on 10.'Tl18 method, of selectively receiving sorbed energy is representative of the direction of said source, absorbing energy from said source, the characteristic of which absorbed energy is noirrepresentative otthe direction of said source, regulating the am- )litudc of one of said ener ies so that the ing disposed to receive as much energy as possible from the giventransmitter;'means for usefully receiving the preponderance of I energy from the given transmitter! and means for varying the damping of said aerialsystem.

12. In an apparatus of the character described, "a plurality of aerials coupled togetherand meansassociated with said aerials to prevent wave excitation in said aerials from producingcomplex oscillations in the system. t 1

13. In an apparatus of the characterj'described, a plurality of aerials having different directional properties and coupled together and means associated with said aerials to prevent wave excitation in said aerials from producing complex oscillations in the system.

14. In apparatus of the character de scribed. a plurality of aerials comprising coupling means between them for equalizing and opposing static energies received thereby and a resistance associated with said aerials and of an order of magnitude to promote the neutralization of said static energies.

15; A unilateral receiving system comprising a closedloop and open aerial, a reversible and adjustable coupling between them for neutralizing the static energies received thereby and a resistance associated with said aerials and of an order of magnitude to prom te sa d neutralization.

16. The method of receiving on two aerials of substantialv different directional properties, radio communication from a given distant transmitter through interference originating out of direction therewith, which consists in setting in opposition to one another, while damping the aerial system, the currents due to the effects on therespective serials, of interference from directions out of d ircction with the given transmitter, While receiving as much energy possible from the given transmitter by each aerial; and usefully receiving the'preponderance of energy from the i I gi veni transmitter.

17. Apparatus for receiving radio communications from a given distant transmitter through interference originating out of direction therewith, which comprises co-operating aerials'of the closed and open types respectively, the closed circuit aerial'being vertical, and tunedto the wave length of the transmitter; means for setting in opposition to one anotherthe currents due to the 'eifects upon the respective 'aerials, of interference originating out of direction with thetransmitter; the loop being pointed asnearly as perinissible toward the transmitterjand means i for usefully receiving the preponderanceof signal energy due to the reception fromthe given transmitter.

= A unilateral receiving system comprising a pluralityof aerials having difi'erent directional properties in any given plane and all arranged to receive signal waves of radio irequency'from any given transmitter and all adapted to receive'statie impulses, adjustable and reyersible couplings betweensaid aei'ials for equalizing and opposing the static energies received for neutralizing them and for adding thefradio frequency signal energies leavinga prpondering amount of signal energy for useful operation, a resistance associated with said aerials and of an orderof magnitude such as to promote theneutralizae tion of static and detector for said added signal impulses. a i

19. Apparatus for receiving radio communications from a given distant transmitter through interference originating out of direction therewith, which comprises co operatingaerials of the closed and open types respectively; means for setting in opposition to one another, the currents due to the efl'ects upon the respective aerials, of interference originating from sources out of direction with the transmitter; the closed circuit aerial bein gvertical, pointed as nearlyas permissible toward. the transmitter and tuned to the wave length thereof; means for usefully receiving the preponderance of energy from the given transmitter; and means for varying the damping of said aerial system. i i

20. Apparatus for receiving radio communications from a given distant transmitter through interference originating out of direction therewith, which comprises a vertical closed circuit aerial; a substantiallynon-directional aerial; means for tuning each of said aerials to the given transmitter; a variable inductance couplingbetween said two aerials; a switch for reversing the connection of at least one of the coupling coils in its aerial; the closed circuit aerial being arrangedto receive as much energy as permissible from the given transmitter; and a local circuit having a variable inductive coupling with each of the coupling coils of said two aerials.

21. Apparatus for receiving radio communications from a given distance transmitter through interference originating out of direction therewith, which comprises co-operating directional and non-directional collectors and a local circuit common to both; inductive couplings between the local circuit and each collector; means for tuning each collector to the desired communication; means for varying the coupling of each collector to said common circuit; a switch for reversing the connections of at least one of the collector-coupling coils in its collector; and a variable resistance in at least one of the collectors.

22. The method of receiving on two aerials of substantially diiferent directional properties and coupled to a common secondary circuit, radio communications from a given distant transmitter through interference originating out of direction therewith, which consists in tuning each collector to the given transmitter; varying the coupling of atleast one of said collectors to said local circuit; causing the electromotive forces in the two collectors due to static to act in opposition to one another; and varying the damping of at least one of said collectors.

23. In an apparatus of the character described, a plurality ofaerials comprising a magnetic loop and open antenna, means comprising adjustable couplings for combining theenergies received by said aerials, means for tuning said aerials, and means for preventing complex wave excitation in said aerials, from producing complex oscillations in the system.

24. In an apparatus of the character described, a plurality of aerials coupled together, means for preventing wave excitation in said aerials from producing complex oscillations in the system, and means for opposing the static energies received by said aerials to eliminate static and leave a prepondering amount of signal energy for useful operation.

GREENLEAF WHITTIER PICKARD. 

